Project Summary/Abstract Infection is a major cause of mortality in transplant recipients, particularly fungal infections. One of the aims of CDC is to perform a program of sentinel surveillance in solid organ and stem cell transplant recipients and to evaluate the impact of new infection programs. A major thrust of this project will be to perform surveillance for fungal, bacterial and viral infections so that the epidemiology of these infections can be precisely determined. Transplant recipients differ quantitatively on their degree of immunodeficiency. This impacts not only infection risk but outcome. Correlation between infection and CD4 positive T cell function will allow the identification of a cohort of patients that could potentially benefit from different preventative strategies. Not only the use of chemoprophylaxis may be warranted in certain patient groups, but diagnosing infections, particularly fungal, at its early stages, while they are treatable, would be another approach. Therefore, another aim of this study is to collect fungal isolates, serum and bronchoalveolar lavage samples that will be used to determine the effectiveness of novel diagnostic tests for invasive fungal and viral infections. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE This project will assess the occurrence of bacterial, viral and fungal infections in the first 30 months following lung, liver and allogeneic hematopoietic stem cell transplantation, with the objective to determine the clinical, immunologic, microbiologic and environmental markers that predict the occurrence of infection. It will also create a repository of fungal isolates and serum and bronchoalveolar lavage specimens, which will be used for evaluation of new diagnostic tests and identification of new pathogens.